@Article{MedeirosSeoBapLeaDek:2022:EfTePH,
               author = "Medeiros, Thais Andrade Galv{\~a}o de and Seoane, Jos{\'e} 
                         Carlos Sicol{\'{\i}} and Baptista, Gustavo Macedo de Mello and 
                         Leal, Philipe Riskala and Dekker, Arnold",
          affiliation = "{Instituto Nacional de Pesquisas Espaciais (INPE)} and 
                         {Universidade Federal do Rio de Janeiro (UFRJ)} and {Universidade 
                         de Bras{\'{\i}}lia (UnB)} and {Instituto Nacional de Pesquisas 
                         Espaciais (INPE)} and {University of Queensland}",
                title = "Effect of temperature and pH on the Millepora alcicornis and 
                         Mussismilia harttii corals in light of a spectral reflectance 
                         response",
              journal = "International Journal of Remote Sensing",
                 year = "2022",
               volume = "43",
               number = "7",
                pages = "2475--2502",
             keywords = "Corals, Thermal stress, Bleaching, Ocean acidification, Spectral 
                         reflectance, Derivative analysis, Linear discriminant analysis.",
             abstract = "The increase in carbon dioxide (CO2) atmospheric levels 
                         contributes to the rise in temperature and ocean acidification; 
                         consequently, it directly impacts coral reefs. The increase in 
                         seawater temperature is the primary factor that causes the 
                         collapse of coral-algal symbiosis, which can be followed by coral 
                         death and, generally, ocean acidification impairs biogenic 
                         calcification and promotes dissolution of carbonate substrata. 
                         These harmful effects on corals associated with the continuous 
                         increase in CO2 atmospheric levels raise widespread concerns about 
                         the coral reef decline, intensifying the efforts to 
                         understand/monitor their effects on these organisms. The objective 
                         of this study was to evaluate the physiological effect of 
                         temperature increase, water acidification (i.e. decrease in pH), 
                         and their effects combined (temperature increase with water 
                         acidification), through the reflectance analyses and maximum 
                         photosynthetic capacity of zooxanthellae (Fv/Fm) in two coral 
                         species: Millepora alcicornis and Mussismilia harttii. Fragments 
                         of four large colonies of each specie were collected, fragmented, 
                         and submitted to four different treatments for 15 days: (i) 
                         control treatment (under identical temperature and pH conditions 
                         observed in the sampling seawater site), (ii) temperature 
                         treatment (with an increase temperature of around \≅2ºC); 
                         (iii) water acidification treatment (with a decrease of nearly 0.3 
                         in pH); and (iv) a treatment of combined effects from water 
                         temperature rising and acidification. Spectral reflectance and 
                         Fv/Fm were measured from samples of these species in a marine 
                         mesocosm. Data of reflectance, first and second-order derivative, 
                         area under the curve, full width at half maximum (FWHM), depth 
                         values and the Fv/Fm were used to classify the coral species and 
                         treatments through the linear discriminant analysis (LDA). Coral 
                         samples were exposed to the increased temperature bleached, whilst 
                         decreased pH caused a slight reduction in reflectance albedo with 
                         minimal effects on Fv/Fm. The combined factors (treatment iv) 
                         triggered a bleaching response, presenting spectral reflectance 
                         and colouring patterns similar to those observed in bleached 
                         corals, especially for M. alcicornis. The two-way ANOVA indicated 
                         statistically meaningful spectral differences between treatments 
                         for the second-order derivatives at 634 nm and for Fv/Fm values. 
                         However, there was no statistically meaningful interaction effect 
                         due to the treatment type and coral species response for the 
                         second-order derivative at 670 nm and to the Fv/Fm values. LDA 
                         classified the corals species and the corals in different 
                         treatment, using their spectral responses and Fv/Fm results, with 
                         high accuracy (96.7% and 73.3%, respectively), reinforcing its 
                         application for coral physiology evaluation and species 
                         classification. The control and combined groups achieved the best 
                         classification scores, with only one misclassification.",
                  doi = "10.1080/01431161.2022.2061875",
                  url = "http://dx.doi.org/10.1080/01431161.2022.2061875",
                 issn = "0143-1161",
             language = "en",
           targetfile = "medeiros_2022_effect.pdf",
        urlaccessdate = "29 jun. 2024"
}